The present invention generally relates to a storage device and a power control method, and is particularly applied to a storage device requiring a reduction in power consumption.
Storage devices contain a plurality of hard disk drives (referred to as a ‘hard disk drive group’ hereinbelow) and are devices in which the hard disk drive group is managed using the RAID (Redundant Array of Independent/Inexpensive Disks) system.
A hard disk drive group stores files compiling a plurality of data and backup data of a plurality of data and so forth, there being time zones in which the storage device does not access the hard disk drive group storing the files and the backup data and so forth depending on the administrator using the data and the content of the data.
Japanese Laid-Open Patent Publication No. 2007-219703 discloses a technology according to which the storage device classifies the data in accordance with the time interval from the point where the data is accessed until the data is accessed the next time, data for which the time interval is long that is not frequently accessed is moved from a high-performance and high-cost hard disk drive to a low-cost hard disk drive of a large capacity, and the rotation of the low-cost hard disk drive of a large capacity is stopped. According to Japanese Laid-Open Patent Publication No. 2007-219703, because the rotation of the low-cost hard disk drive of a large capacity that stores the classified data is stopped, energy savings can be obtained.